In the first stage, I pumped up the shooting speed and bullet speed, and also pumped up the damage & accuracy a little. Then, on the first ability, I chose vampirism, and started pumping only it. After a few improvements, vampirism will heal you a lot (!) of health almost every shot. After that, when the pumping of vampirism reaches its limit, it will be much easier, and even a bunch of turtles that come close to you will not be able to kill you, since you are constantly being treated. And then everything will go much easier, and it will be fun to pump in the rest of the abilities.
